The power combining networks are essential assemblies in radar applications. The coverage range of the radar is limited by the available power. In this project, we aimed to construct a huge assembly to combine 32- power amplifier modules. The number of modules is large to reach 5000 watts of CW power in X-band. Each power amplifier module can provide 150-160 watts of continuous power; accordingly, we need a 32-way combining assembly to ensure the required output power level. Through this project, we have various technological uncertainties and obstacles to overcome. The objective bandwidth is a full band WR90 standard from 8.2 to 12.4 GHz, which is a quite large bandwidth. The matching level will deteriorate significantly as the 32-way will involve five successively cascaded stages. Moreover, the objective isolation level should be maintained among all input ports over the full band operation. The isolation level is a mandatory condition to protect the power amplifier modules from inter-module coupling, which can cause complete module damage. The power handling of the assembly must comply with the anticipated maximum output power. This adds significant limitations to the final stage design to ensure the maximum power handling capability of the entire system. In addition, the phase variation is a critical specification of the entire assembly. If the phase difference between various input ports exceeds a certain level, this will reduce the output power level.
On the other hand, the mechanical aspects are essential characteristics of the system, where we need to ensure the mechanical stability for the complete assembly. The system is large and has a relatively high weight. The mechanical challenges are among the critical challenges in this project. The weight of the assembly components must be considered, and the joint points forces must be supported by having extra brackets to ensure the weight balance. The assembly integration, as well as the attachment of the termination, is also a challenging aspect to ensure in-phase characteristics among all input ports. This must be ensured by the adequate components’ orientation.
